.element{
    margin: auto;
    width: 1000px;
}
.user{
    text-align: center;
    line-height: 40px;
    color: white;
}
li{
    width: 200px;
    text-align: center;
}
#btn1,
#btn2,
#btn3,
#btn5,
#btn6{
    width: 200px;
    border: none;
    border-radius: 0;
}
.headMain{
    width: 1450px;
    height: 41px;
    margin: auto;
    background-color: #6C757D;
    border-top: 1px solid #6C757D;
}
.element1:after{
    clear:both;
    display:block;
    content:"";
}
.element>div{
    float: left;
    width: 200px;
    height: 40px;
    background-color: #6C757D;
}